Is this barrel chrome lined, or is the crown just damaged?

Status
Not open for further replies.
GJgo

GJgo

Member
Joined
Feb 12, 2007
Messages
966
Location
Western Colorado
I recently picked up a DPMS Predator. After I gave it a full cleaning I noticed something weird on the crown, and I can't decide if it's chrome lined or just damaged.

The reason I think it might be lined are:
- There appears to be some chrome spillage over the crown..?
- I cleaned it thouroughly with Barnes CR-10 & there was no blue whatsoever on any patch. I have never seen this before.
- There's a chrome-ish look at the edge of the crown.
- There's also a chrome-esque look to the internal bore of the gas port in the bolt.

The reason I think it might not be lined are:
- The barrel is not stamped "chrome".
- from one angle it looks like the crown might just be cut crooked?

Here's a photo from one side-
8516651945_5b68b5ba77_z.png

And here's a photo when I turn the barrel 180°-
8516651907_d4a645a5f3_z.png

So, what do you guys think? If it's not lined, I'm going to get a PTG crowning tool & clean it up. If it is lined apparently I can't do that, and I'll have to live with the weird cut in the crown.
 
Last edited:
From the photo it looks like a defective crown machining. How does it shoot? If it shoots fine, then forget it.
 
I third that motion. If the rifle shoots acceptably than I would not touch the crown. I have learned the hand tools used for re-crowning will not hold a candle to a crowning bit with the barrel chucked up in a lathe.
 
Well, it doesn't shoot very well for my standards but then again I don't expect an AR to shoot like my bolt rifles do. I tried a number of different ammo types off the bench from 40 grains to 75 grains, and the only thing it shot under an inch was some Hornady 55 gr flat base soft points. I was really expecting the 75 grainers to shoot better than they did in the 8 twist barrel.
 
Well, it doesn't shoot very well for my standards but then again I don't expect an AR to shoot like my bolt rifles do
Click to expand...

Its probably chrome, barrels are not chrome plated to enhance accuracy.
 
Big difference between bumper chrome and hardchrome. Even if both are electroplated.

I've seen quite a few ARs that shoot tiny groups. The Di action has potential for making scary accurate rifles w/o lots of work.

If the barrel doesn't shoot decent groups I'd get it recrowned. I'd also get the throat checked out. .223's do burn out the throat fast.

BSW
 
That crown looks like it has a defect. If the rifle isn't grouping the way it should (how does it compare to other DPMS Predators?), I would have it recrowned by a competent gunsmith.
 
From my understanding DPMS doesn't use any chrome lined barrels, but I may in fact be wrong.

I can't recall ever seeing any manufacturer produce a chrome lined bull barrel for that matter.

Safe bet is that it's stainless steel. I agree that the crown doesn't look good, but would go ahead and shoot it a good bit before fixing problems you think that it might have.
 
I have not seen everything but I do not believe I have ever saw a heavy varmint type barrel chromed before. I had a colt hbar that was chromed but it had flash hider and bayo lug.That was the most accurate AR I ever fired
 
And the 75 grain bullet might be stretching it for a 1:8 twist. It is the heaviest I'd go but a 1:7 is really ideal for it.
 
Thanks guys. I'm going to run it by DPMS, see if they have a fix before I think about crowning it myself. :)
 
DPMS does in fact chrome line some of their barrels, but according to them they are stamped "chrome". I have an email in to them to see if they'd like to take care of the problem, if not I'll just re-crown it & call it good. I'll post when I have some answers- thanks again.

P.S. I just took the pics with my iPhone 4S!
 
So DPMS said to send the upper back in & they would "take care of it", but they wouldn't give me any details. Nice offer of them, but with the state of things these days & how busy I'm sure they are I decided to just handle it myself. So, I re-crowned it using a PTG 11° tool. As it turns out the barrel is stainless with a black coating on it! Good thing I have some Caswell stainless blackener around or I'd have a real shiny spot hanging out there.

8695088538_cc0628b046_z.png

The yellow color in the pic is just the indoor lighting, it's more of a polished stainless silver color. Fingers crossed it shoots now as good as it looks.
 
Now, how does it shoot post-recrown? That's the important question. One of my mausers was shooting all over the place and I was on the verge of rebarreling it. (12"+ groups at 100 yards.) The bore wasn't great or anything, but shouldn't have been that bad. Prior to shipping it off to the smith, I recrowned it with a Lee case trimmer followed by a brass screw + lapping compound.

Dropped the groups to around 1.5" @ 100 yards. A better trigger (Bold trigger) dropped it to a consistent 1".

With an asymmetric bevel on the crown like yours had, the precision had to have been affected.

Matt
 
Status
Not open for further replies.

Similar threads

MTMilitiaman
  • Locked
Chrome lining a barrel
Replies
17
Views
10K
Owen
O
N
  • Locked
Recrowing a Russian CL'ed SKS Barrel
Replies
2
Views
467
NC-Mike
N
D
  • Locked
crowning a chrome lined barrel?
Replies
2
Views
491
Traveler
T
C
  • Locked
Cleaning/Crown Damage Q?
Replies
8
Views
849
JWarren
J
N
  • Locked
Chrome Lined Barrel
Replies
11
Views
2K
JohnKSa
JohnKSa
Back
Top